1. Field of the Invention
Systems consistent with the present invention relate to a 2D-3D image switching display, and more particularly, to an image display system able to switch easily between a 2D image and a 3D image.
2. Description of the Related Art
A three-dimensional (3D) image is formed according to the principle of stereoscopic vision through the eyes of a human being. Binocular parallax, which is generated due to distance of about 65 mm between the human eyes, can be considered as the most important factor inducing a cubic effect. General stereoscopic display techniques are roughly classified into a glasses stereoscopic display technique and a glass-less stereoscopic display technique. In the glass-less stereoscopic display technique, a 3D image can be obtained by separating left and right images without using glasses. In this regard, a parallax barrier 3D display apparatus or a lenticular 3D display apparatus can be used.
In the case of the parallax barrier 3D display apparatus, a left eye image and a right eye image are displayed on alternating vertical pixel columns and separated through a very thin vertical lattice, that is, a barrier. The left eye image in a vertical column and the right eye image in a vertical column are separated by the barrier, so that the left and right eyes respectively receive images from different view points to thereby form a 3D image.
In the case of the lenticular 3D display apparatus, the images corresponding to the left eye and the right eye are formed on a focus surface of a lenticular lens, and the images are observed through the lenticular lens, and thus a separated stereoscopic image is separated to be displayed on the right eye and the left eye according to directional characteristic of the lenticular lens.
Meanwhile, a 2D-3D image switching display apparatus has been developed in order to satisfy the users' requirements for seeing a 2D image in the 3D display apparatus. U.S. Patent Publication No. 2004/0041747 A1 discloses a conventional display apparatus which can display a 2D image using a lenticular 3D display apparatus. FIGS. 1A and 1B are views illustrating a related art 2D-3D image switching apparatus disclosed in U.S. Patent Publication No. 2004/0041747 A1.
Referring to FIGS. 1A and 1B, the related art display apparatus includes a display device 2 including a plurality of left eye pixels 41 and a plurality of right eye pixels 42 which are alternately disposed, and a first optical unit 31 and a second optical unit 32 in which lenses are alternately disposed to refract light from the pixels.
The lenses of the first optical unit 31 and the second optical unit 32 are arrayed at the same periods. When the first optical unit 31 is moved by half of the period of the lens array with respect to the second optical unit 32, a 3D image is displayed. When the first optical unit 31 is moved so that the period of the first optical unit 31 may correspond to that of the second optical unit 32, a 2D image is displayed. In the related art display apparatus, the first optical unit 31 is moved in a direction 11 perpendicular to an optical axis in order to switch between the 2D image and the 3D image. However, since the first optical unit 31 is not moved in a horizontal direction, but is moved in a curved direction along the lens shape of the second optical unit 32, a movement mechanism is complicated.
When the 3D image is displayed, the first optical unit 31 is not easily moved by half of the pitch of a lens cell of the second optical unit 32, and there is almost no cross-talk in an optimized viewing point in 3D mode. However, at this time, cross-talk is greatly increased in a middle viewing zone other than viewing point, and thus an image deteriorates and the brightness of the image is reduced. Accordingly, a viewing zone in which the 3D image can be observed without cross-talk is quite narrow.
FIG. 2 is a view illustrating a related art 2D-3D display apparatus disclosed in U.S. Pat. No. 6,069,650. The related art 2D-3D display apparatus includes a lenticular means 115. The lenticular means 115 includes a lenticular sheet 130, liquid crystal layer 138, and a plate 136. A thin film 134 is formed between the lenticular sheet 130 and the liquid crystal sheet 138. The lenticular sheet 130 includes a lenticular element 116. In addition, the related art 2D-3D display apparatus includes a power source 140 for supplying power to the liquid crystal sheet 138 and a switch 141.
In the related art 2D-3D display apparatus of FIG. 2, according to the switching state of the power source 140, the refraction indexes of the liquid crystal layer 138 and the lenticular sheet 130 may be the same or different. When the refraction indexes of the liquid crystal sheet 138 and the lenticular sheet 130 are the same, light incident on the lenticular sheet 130 is transmitted through the lenticular sheet 130 and liquid crystal layer 130 without being refracted to display an image of a 2D mode. On the other hand, when the refractive indexes of the liquid crystal sheet 138 and the lenticular sheet 130 are different, the lenticular sheet 130 separates an image and displays a left eye image and a right eye image to embody an image of a 3D mode.
In order to display a 3D image having good quality, the thickness of the liquid crystal sheet 138 should be very thin. However, since a lenticular surface corresponding to a lenticular sheet is formed on a lower surface of the liquid crystal sheet 138, there is a limit in forming the thin liquid crystal sheet 138. In addition, since a manufacturing technique of the lenticular sheet formed by filling a lens with liquid crystal is not generalized and it is difficult to switch a liquid crystal layer, the reliability and performance of a related art 2D-3D display apparatus is low.